According to the U.S. Energy Information Administration’s latest inventory of electric generators, 9.1 gigawatts (GW) of electric generating capacity is scheduled to retire in 2021.
In total, it appears that 30 plants (nuclear, coal, petroleum, and others) will be retired in 2021. Five nuclear reactors are included in the closure list—Indian Point-3, Byron (two units at the plant), and Dresden (two units at the plant). Those three plants produce 5.1 GW of power, accounting for more than half of the total capacity expected to be retired.
The EIA report notes, "If all five reactors close as scheduled, 2021 will set a record for the most annual nuclear capacity retirements ever."
There have been recent reports, however, that the state of Illinois could legislate support for Exelon, which would result in their Byron and Dresden plants being saved from an early retirement. Doing so would keep 4.1 GW of carbon-free power on the grid.